Means for splash separation on paper machines

ABSTRACT

A means for splash separation at a dandy roll on a fourudrinier machine is disclosed. The means comprises a doctor blade and a cover in order to separate and divert water further from the dandy roll. A rotating roll is positioned for collecting the separated water from the dandy roll. An additional doctor blade is used for wiping off the water from the rotating roll and for diverting it into a tub. The water leaves the tub at one or both short sides, which are open. In order to divert the water towards the respective short end, the tub is positioned or shaped inclined towards one or both short ends.

FIELD OF THE INVENTION

[0001] The present invention pertains to paper making machines andrelates more particularly to a means for collecting and conveying awaywater splash from the dandy roll in a fourudrinier machine.

PRIOR ART

[0002] Dandy roll means are used in fourudrinier machines formanufacturing of paper. The dandy roll normally rests with its weight onthe paper wire cloth prior to the drying section and is an open, wirecloth covered cylinder. Its function is to disintegrate fiber flocks andit is some-times called laid dandy roll. In the nip between the paperwire cloth and the dandy roll water penetrates through the apertures inthe wire cloth of the dandy roll while the stock layer is deflocculated.The water, which thereupon is slung from the circumference of the dandyroll by means of the centrifugal force, is collected in so-called splashseparators and is conveyed away from the paper wire cloth.

[0003] In existing splash separation means one or more doctor blades areused, which are positioned closely to the dandy roll, so that anunderpressure is generated, which facilitates for the water to leave thedandy roll. There is always a certain amount of fiber material and othersolid matter which follows with the water, whereby said material tendsto get stuck in the edge of a tub underlying the splash separator. Thetub is located directly under the dandy roll in order to capture thewater splash and it is difficult to reach the tub. The splash separatorhas to be cleaned permanently in order to remove the accumulated solidmatter. Due to the location of the tub production has to be stoppedtemporarily when cleaning the tub, which involves an economic loss.

SUMMARY OF THE INVENTION

[0004] The object of the invention is to collect and convey water splashfrom the dandy roll with a simple design, whereby the need for cleaningthe splash separator is eliminated or at least substantially reduced. Atthe same time cleaning of the tub is facilitated.

[0005] This object is achieved by installation of a rotating roll, whichis positioned under the water splash. The water splash is captured bythe roll and is wiped off the roll by means of a doctor blade, which ispositioned close to the roll. The water, which is wiped off, is conveyeddown into a tub and subsequently out of the machine.

[0006] The invention is based on the understanding that it is possibleto position the tub, which receives the splash water into a more easilyaccessible position by positioning a roll under the dandy roll. The tubat the roll replaces the tub positioned under the dandy roll accordingto the prior art. Thus, by using the roll, the tub gets more easilyaccessible and in that way it gets easier to clean.

BRIEF DESCRIPTION OF THE FIGURES

[0007] The invention will be explained more in detail below withreference to the appended drawings. In these

[0008]FIG. 1 shows a side view of dandy roll means according to theinvention and

[0009]FIG. 2 shows a top view of the means according to FIG. 1, partlyin a cutaway cutting section for elucidating purposes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0010] The dandy roll 1 rests with its weight on the paper wire 2immediately before the drying section. A rotating roll 3 is arrangedclose to the dandy roll 1 in order to capture water splash from thedandy roll 1. The roll 3 is arranged parallell to the dandy roll 1 andhas normally the same length as the dandy roll 1. The roll 3 ispositioned in such a position that it completely lies under a imaginaryhorizontal plane, which goes through the center of the dandy roll 1. Theroll 3 is furthermore positioned in such a way that a gap is formedbetween the roll 3 and the dandy roll 1. The roll 3 is by means of afastening means 7 attached to two sliding ferrules 6, which in turn arepositioned on slide bars 5. The position of the roll 3 is verticallyadjustable by means of fastening means 7 and its position ishorizontally adjustable by moving the sliding ferrules 6 along the slidebars 5. The fastening means 7, the sliding ferrules 6 and the slide bars5 facilitate maintenance and replacement of the roll 3. In otherembodiments other types of fastening means are used. The roll 3 isrotated in a conventional way by means of a motor 13, which is indicatedin FIG. 2.

[0011] A doctor blade 9 is positioned at the dandy roll 1, on a levelabove the center line of the dandy roll 1 for scraping away fluid fromthe dandy roll 1. The doctor blade 9 is attached to a support which isfastened to the dandy roll means. The direction of the doctor blade 9and the distance to the envelope surface of the dandy roll 1 areadjustable for a maximum effect. The water can flow from both theunderside and the upper side of the doctor blade 9. The doctor blade 9extends over the whole length of the dandy roll 1 and is positionedunder a cover 11 when this is fold down. It is even possible to have aplurality of doctor blades 9 positioned at different heights.

[0012] A cover 11 is positioned above the roll 3 and acts as a shieldingdevice for collecting and conveying down splashwater from the dandy roll1 to the roll 3. The cover 11 consists of a wall at each end of thedandy roll 1 and a wall in parallell with the dandy roll 1, whereby saidwall is joined with the other two walls at the ends of the dandy roll 1.The wall of the cover 11 in parallell with the dandy roll 1 ispositioned aligned with or substantially aligned with the outercircumference of the roll 3 at the circumferencial part which is turnedaway from the dandy roll 1. The cover 11 is in the illustratedembodiment journalled upwardly tiltable with respect to the dandy roll1. In other embodiments the cover 11 is fixed and can not be tiltedupwards. The cover 11 is shaped and positioned in such a way that anywater splash, which flows off the walls of the cover 11 lands on theroll 3 and is diverted away.

[0013] A shield 8 shields the dandy roll 1 from the paperweb 2 butfunctions at the same time as a part of the splash separator. A doctorblade 4 leads water splash from the roll 3 down into a tub 10. Thedoctor blade 4 extends along the whole length of the roll 3. Even ifonly one doctor blade 4 is shown, which is the normal case, otherembodiments (not shown) can use a plurality of doctor blades 4positioned at different heights. The doctor blade 4 must abut againstthe roll 3, so that the water only can flow off the upper side of thedoctor blade 4. As little water as possible, and preferably no water atall, should follow with the roll 3 behind the doctor blade 4.

[0014] From the tub 10 the water is drained off the machine. The size oftub 10 is adapted to the size of the roll 3 as well as to the size ofthe shield 8. The tub 10 can be shaped with rectangular or circularcross section. The water can either be drained from one short side 14 ofthe tub 10 or from both short sides 14 of the tub 10. Usually this isdone by the one or both short ends 14 being open. In this connection thetub 10 is positioned or shaped inclined towards one or both ends 14 ofthe tub 10, depending where the openings of tub 10 are situated. The tub10 is also provided with two tubes 12 on the inside, whereby said tubes12 are steam coils of an existing steam system. The steam is used toheat up the tub 10 and, thus, formation of condense is avoided on thewalls of the tub 10.

[0015] The roll 3 is either provided as a solid or a hollow roll, whosecircumferential surface preferably is manufactured of a hard rubbermaterial. Plastic or ceramic materials are generally also suitable. Theroll 3 can alternatively be covered or coated with a material, which issuitable for capturing water splash. Thus, the material of the rollsurface can be any material, which gives a smooth but not waterrepelling surface, which is also valid for covering material or coatingmaterial. An important criterium for the surface of the roll 3 is thatit is smooth because all water will be scraped away from the roll 3 tothe tub 10 in order to be conveyed further.

[0016] The diameter of the roll 3 is adapted to the outer diameter ofthe dandy roll 1. The diameter determines also how large the resultingcircumferential surface is for capturing the water splash. The size ofthe circumferential surface is to be adapted in a way that all splash,which is scraped away from the dandy roll wire 1, lands on the roll 3.The diameter and speed of roll 3 influence the function in such a waythat a larger diameter at a certain rotational speed results in a higherperiferical speed. If the speed is too high the water is slung from theroll 3 while a too low speed does not have the desired effect. Thediameter of the roll 3 is also determined by the space around the dandyroll 1.

[0017] The periferical speed of the roll 3 can vary between 10-400m/min, but usually lies in the range of 50-250 m/min. The perifericalspeed of the dandy roll 1 varies from machine to machine and has aspeed, which is about 0,5-1,5% higher than that of the paperweb. Thespeed is normally from approximately 400 m/min up to approximately 1000m/min. The diameter of the dandy roll 1 usually varies betweenapproximately 1000 mm to approximately 2500 mm. The higher the speed,the more water has to be scraped away.

[0018] In operation, the splash water from the dandy roll 1 is scrapedaway by means of the upper doctor blade 9. The splash water leaves thedandy roll 1 also by means of the centrifugal force caused by therotation of the dandy roll 1. Thanks to the cover 11 and the force ofgravity the splash water will fall down on the roll 3. The water, whichhas been caught by the roll 3, is scraped away from the roll 3 by meansof the doctor blade 4 and is collected in the tub 10 under the doctorblade 4. Finally, the water leaves the tub 10 at one or both short sides14, depending on whether only one or both short sides 14 are open.

1. Means for splash separation at a dandy roll (1) of a fourudriniermachine, comprising a means (9, 11) for detaching and further conveyingwater from the dandy roll (1) and a rotating roll (3) for capturing thedetached water from the dandy roll (1), characterized in that the roll(3) is located in a position completely under an imagined horizontalplane, which goes through the center of the dandy roll (1).
 2. Meansaccording to claim 1, characterized in that there is a gap between thesurface of the roll (3) and the surface of the dandy roll (1), that theroll (3) is parallell to the dandy roll (1) and that the roll (3) andthe dandy roll (1) have the same length.
 3. Means according to claim 1or 2, characterized in that the means for detaching and furtherconveying water from the dandy roll (1) comprises a doctor blade (9)positioned at the dandy roll (1) on a level above the center line of thedandy roll (1) and a cover (11), whereby said cover (11) has threejoined walls, whereby one wall is substantially parallell to the dandyroll (1) and two walls are at either end of the dandy roll (1).
 4. Meansaccording to any of the preceding claims, characterized in that a doctorblade (4) is positioned close to the roll (3) for scraping off waterfrom the roll (3) and that a tub (10) is positioned under the doctorblade (4) for collecting the detached water, whereby said tub (10) ispositioned by the side of the roll (3).
 5. Means according to any of thepreceding claims, characterized in that the diameter of the roll (3) andthe rotational speed are adapted to a desired path of movement of thedetached water, whereby the roll (3) rotates at a periferical speed of10-400 m/min and preferably 50-250 m/min.
 6. Means according to any ofthe preceding claims, characterized in that the roll (3) is solid orhollow and that the circumferential surface is made of a material, or iscovered or coated with a material, which is suitable for capturing watersplash, and which gives the roll (3) a smooth surface.
 7. Meansaccording to any of the preceding claims, characterized in that the roll(3) rests on sliding bars (5) by way of fastening means (7) and slidingferrules (6) and that the position of the roll (3) can be adjusted bothvertically and horizontally by means of the fastening means (7), thesliding ferrules (6) and the sliding bars (5).
 8. Means according to anyof claims 4-7, characterized in that the tub (10) has a circular orrectangular section, that the tub (10) is open at one or both shortsides (14) in order to divert away collected water and that the tub (10)receives a tube (12), which constitutes a part of a steam coil.
 9. Meansaccording to any of claims 4-8, characterized in that the doctor blade(4) abuts so tightly against. the roll (3) that the entire amount ofwater is diverted over the doctor blade (4).
 10. Means according any ofclaims 4-9, characterized in that the respective doctor blade (4, 9)extends along the length of the whole roll (3) and the length of thedandy roll (1) and/or that a plurality of doctor blades (4, 9) arepositioned above each other at the roll (3) and/or the dandy roll (1).11. A device for splash separation at a dandy roll of a fourudriniermachine, comprising: a means for detaching and further conveying waterfrom the dandy roll; a rotating roll for capturing the detached waterfrom the dandy roll, wherein the rotating roll is located in a positioncompletely under an imagined horizontal plane, which goes through thecenter of the dandy roll.
 12. The device according to claim 11, whereinthere is a gap between the surface of the rotating roll and the surfaceof the dandy roll, wherein the rotating roll is parallel to the dandyroll and the rotating roll and the dandy roll have the same length. 13.The device according to claim 11, wherein the means for detaching andfurther conveying water from the dandy roll comprises a first doctorblade positioned at the dandy roll on a level above the center line ofthe dandy roll and a cover, whereby one wall is substantially parallelto the dandy roll and the two walls are at either end of the dandy roll.14. The device according to claim 13, wherein a second doctor blade ispositioned close to the rotating roll for scraping off water from therotating roll and a tub is positioned under the second doctor blade forcollecting the detached water, whereby said tub is positioned by theside of the rotating roll.
 15. The device according to claim 11, whereina diameter of the rotating roll and a rotational speed are adapted to adesired path of movement of the detached water, whereby the rotatingroll rotates at a periferical speed of 10-400 m/min.
 16. The deviceaccording to claim 15, wherein rotating roll rotates at a perifericalspeed of 50-250 m/min.
 17. The device according to claim 11, wherein therotating roll is solid or hollow and the circumferential surface is madeof a material which is suitable for capturing water splash, and whichgives the rotating roll a smooth surface.
 18. The device according toclaim 11, wherein the rotating roll is solid or hollow and thecircumferential surface is covered or coated by a material which issuitable for capturing water splash, and which gives the rotating roll asmooth surface.
 19. The device according to claim 11, wherein therotating roll rests on sliding bars by way of fastening means andsliding ferrules and the position of the rotating roll can be adjustedboth vertically and horizontally by means of the fastening means, thesliding ferrules and the sliding bars.
 20. The device according to claim14, wherein the tub has a circular section and the tub is open at partof the circular section in order to divert away collected water and thetub receives a tube which constitutes a part of a steam coil.
 21. Thedevice according to claim 14, wherein the tub has a rectangular sectionand the tub is open at at least one short side of said rectangularsection in order to divert away collected water and the tub receives atube which constitutes a part of a steam coil.
 22. The device accordingto claim 14, wherein the second doctor blade abuts so tightly againstthe rotating roll so that substantially the entire amount of water isdiverted over the second doctor blade.
 23. The device according to claim14, wherein at least one first doctor blade extends along the length ofthe dandy roll and at least one second doctor blade extends along thelength of the rotating roll.